KR20070118016A - Photosensitive compound, photosensitive composition, method for resist pattern formation, and process for device production - Google Patents

Abstract

A photosensitive compound is provided to need no heating after exposure when a resist pattern is formed, and form a resist pattern having small line edge roughness. A photosensitive compound comprises at least two structural units represented by the following formula (1) in a molecule. In the formula, R1 is a hydrogen atom or alkyl group, at least one of R2, R3, R4, R5, and R6 is a nitro group and the rest is a group selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a phenyl, a naphthyl group, and an alkyl group of which some or all hydrogen atoms are substituted with fluorine atoms, and R7 is a substituted or unsubstituted phenylene group or naphthylene group.

Description

Photosensitive compound, photosensitive composition, method of forming resist pattern and manufacturing method of device {PHOTOSENSITIVE COMPOUND, PHOTOSENSITIVE COMPOSITION, METHOD FOR RESIST PATTERN FORMATION, AND PROCESS FOR DEVICE PRODUCTION}

1 illustrates a photochemical reaction of the photosensitive composition of the present invention;

2A and 2B illustrate photochemical reactions of conventional chemically amplified resists;

3 illustrates the dependence of the dissolution rate of the photosensitive compound on the developer to the nitrobenzyl ether group introduction ratio in the photosensitive compound;

4 shows extinction coefficients of coating films of photosensitive compounds A to D and PHS (polyhydroxystyrene) in Example 4 of the present invention;

5A is an atomic force microscope (AFM) photograph of a resist pattern with a pitch of 90 nm using photosensitive composition M;

5B is an atomic force micrograph of a resist pattern with a pitch of 90 nm using photosensitive composition A;

6 is an atomic force micrograph of a resist pattern 1 μm ² having a film thickness of 30 nm and a pitch of 160 nm using the photosensitive composition M;

7 is an atomic force micrograph of a resist pattern 1 μm ² having a film thickness of 20 nm and a pitch of 160 nm using the photosensitive composition M;

8 is an atomic force micrograph of a resist pattern 1 μm ² having a film thickness of 10 nm and a pitch of 160 nm using the photosensitive composition M;

9 is an atomic force micrograph of a resist pattern 1 μm ² having a film thickness of 20 nm and a pitch of 160 nm using the photosensitive composition A;

10 is an atomic force micrograph of a resist pattern 1 μm ² having a film thickness of 10 nm and a pitch of 160 nm using the photosensitive composition A. FIG.

<Description of the symbols for the main parts of the drawings>

101: alkali-soluble group 102: alkali-soluble group

103: photoreaction point 201: alkali-soluble group

204: resist layer

The present invention relates to a photosensitive compound, a photosensitive composition comprising the photosensitive compound dissolved in a solvent, a method of forming a resist pattern using the photosensitive composition, and a method of manufacturing a device using the method of forming the resist pattern.

In recent years, in the field of various device industries that require microfabrication including semiconductor devices, higher density and higher integration of devices are required. In the semiconductor device manufacturing process, an important technique for forming a fine pattern is photolithography.

In photolithography, a technique for stable microfabrication with a precision of 100 nm or less is employed. Therefore, the resist used for photolithography also needs to be able to form a pattern with the precision of 100 nm or less.

Diazonaptoquinone-novolak-type resists utilizing the dissolution inhibiting effect of diazonaptoquinone compounds on phenol resins are widely used (USP 4,859,563).

The diazonaphthoquinone-novolak-type resist composed of a low molecular weight phenol resin cannot be affected by the dissolution inhibiting effect of the diazonaphthoquinone compound, resulting in low development contrast between the exposed portion and the unexposed portion.

In recent years, chemically amplified resists have been used as resists of higher resolution than diazonaphthoquinone-novolak resists. In chemically amplified resists, an acid (H ⁺ ) is generated by actinic light irradiation, and the generated acid catalyzes the deprotection reaction of an alkali-soluble group protected with an acid-decomposable protecting group to alkali-solubilize the resist (Journal of Photopolymer Science and Technology, 17, 435 (2004).

When fabricating a resist pattern of a chemically amplified resist, the resist is heat treated before development in order to promote the deprotection reaction catalyzed by the acid generated in the exposure region.

In this heat treatment, the acid diffuses at a distance of about 10 nm by heat (see "Proc. SPIE", 6154, 710, 2006). This acid diffusion causes fine unevenness at the edge portion of the pattern, that is, line edge roughness (LER), thereby lowering the resolution.

LER also depends on the molecular weight of the base compound. The base compound herein refers to a compound having an alkali soluble group or a protected alkali soluble group in the resist composition.

Since the base compound is dissolved in the developer in molecular units, the larger the molecular weight of the base compound, the larger the LER.

The lower the molecular weight base compound, the lower the glass transition temperature and melting point. When the chemically amplified resist is heated before the development treatment at a temperature higher than its glass transition temperature, the formed acid diffuses over a longer distance and the resolution becomes lower.

Therefore, the base compound of the chemically amplified resist needs to have a glass transition temperature higher than the deprotection reaction temperature under the acid catalyst. This requirement limits the low LER design of chemically amplified resists by the use of low molecular weight resists.

The present inventors found that in the pattern formation by near-field light exposure, when the chemically amplified resist diluted with the organic solvent was applied to a thickness of 10 nm, the LER of the obtained resist pattern was undesirably larger.

J. Org. Chem. 2003, 68, 9100 (2003) disclose caged compounds with potential physiological activity formed by nitrobenzyl-etherifying phenolic hydroxyl groups of capsaicin. However, this compound is not intended for use as a pattern forming material.

In addition, J. Appl. Polym. Sci., 33, 1763 (1987), discloses a photosensitive polyimide resist with nitrobenzyl groups. This resist becomes alkali-soluble by light irradiation, and can leave nitrobenzyl from a polyimide. In addition, the polymer of this resist is solubilized by generating a carboxylic acid group (COOH) by removal of nitrobenzyl. However, in this resist, due to the swelling of the resist polymer caused by the reaction of the carboxylic acid with the alkaline developer, a low resolution such as a micrometer order is imparted.

Summary of the Invention

The present invention relates to a photosensitive compound comprising two or more structural units represented by the following general formula (1) in a molecule:

(Wherein R ₁ is a hydrogen atom or an alkyl group; at least one of R ₂ , R ₃ , R ₄ , R ₅ and R ₆ is a nitro group, and others are a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, A phenyl group, a naphthyl group, and a group selected from the group consisting of an alkyl group in which some or all of the hydrogen atoms are substituted with fluorine atoms, R ₇ is a substituted or unsubstituted phenylene group or a naphthylene group.

The photosensitive compound may include two or more structural units represented by the following general formula (2) in a molecule:

Wherein R ₇ is as defined above.

The photosensitive compound may contain two or more structural units represented by the following general formula (3) in a molecule:

Wherein R ₇ is as defined above.

The photosensitive compound may contain two or more structural units represented by the following general formula (4) in a molecule:

Wherein R ₇ is as defined above.

The photosensitive compound may contain two or more structural units represented by the following general formula (5) in a molecule:

Wherein R ₇ is as defined above.

The present invention relates to the photosensitive compound comprising two or more structural units represented by the following general formula (6) in a molecule:

(Wherein R ₁ is a hydrogen atom or an alkyl group; at least one of R ₂ , R ₃ , R ₄ , R ₅ and R ₆ is a nitro group, and others are hydrogen atoms, halogen atoms, alkyl groups, alkoxy groups, phenyl groups) , A naphthyl group, and a group selected from the group consisting of alkyl groups in which some or all of the hydrogen atoms are substituted with fluorine atoms, R ₇ is a substituted or unsubstituted phenylene group or a naphthylene group.

The photosensitive compound may include two or more structural units represented by the following general formula (7) in a molecule:

Wherein R ₇ is as defined above.

The photosensitive compound may contain two or more structural units represented by the following general formula (8) in a molecule:

Wherein R ₇ is as defined above.

The photosensitive compound may contain two or more structural units represented by the following general formula (9) in a molecule:

Wherein R ₇ is as defined above.

The photosensitive compound may include two or more structural units represented by the following general formula (10) in a molecule:

Wherein R ₇ is as defined above.

The present invention relates to poly (hydroxystyrene), wherein the hydrogen atoms of two or more phenolic hydroxyl groups are substituted with a substituent represented by the following general formula (11) or (12):

(Wherein R ₁ is a hydrogen atom or an alkyl group; at least one of R ₂ , R ₃ , R ₄ , R ₅ and R ₆ is a nitro group, and others are hydrogen atoms, halogen atoms, alkyl groups, alkoxy groups, phenyl groups) , A naphthyl group, and an alkyl group in which some or all of the hydrogen atoms are substituted with fluorine atoms)

The present invention relates to carlix arene, wherein a hydrogen atom of two or more phenolic hydroxyl groups is substituted with a substituent represented by the following general formula (11) or (12):

(Wherein R ₁ is a hydrogen atom or an alkyl group; at least one of R ₂ , R ₃ , R ₄ , R ₅ and R ₆ is a nitro group, and others are hydrogen atoms, halogen atoms, alkyl groups, alkoxy groups, phenyl groups) , A naphthyl group, and an alkyl group in which some or all of the hydrogen atoms are substituted with fluorine atoms.

The present invention relates to a novolak resin, wherein a hydrogen atom of two or more phenolic hydroxyl groups is substituted with a substituent represented by the following general formula (11) or (12):

(Wherein R ₁ is a hydrogen atom or an alkyl group; at least one of R ₂ , R ₃ , R ₄ , R ₅ and R ₆ is a nitro group, and others are hydrogen atoms, halogen atoms, alkyl groups, alkoxy groups, phenyl groups) , A naphthyl group, and an alkyl group in which some or all of the hydrogen atoms are substituted with fluorine atoms.

The present invention relates to a photosensitive composition comprising at least one of the aforementioned compounds dissolved in an organic solvent.

The present invention provides a process for forming a photosensitive resist layer by applying the photosensitive composition on a substrate; Selectively irradiating the resist layer with radiation; And developing the radiation irradiation part to form a pattern of the resist layer.

In the method of forming the resist pattern, a resist layer removable by plasma etching and another resist layer having resistance to plasma etching can be laminated on the substrate, and the photosensitive property on the layer having resistance to plasma etching. A resist layer can be formed.

In the method of forming the resist pattern, the photosensitive resist layer may be formed to a layer thickness of 20 nm or less.

In the method of forming the resist pattern, irradiation of the radiation may be performed by near-field light.

This invention relates to the manufacturing method of the device characterized by creating a device on a board | substrate using the formation method of the said resist pattern.

The photosensitive compound of this invention does not require the heating after exposure in resist pattern formation. For this reason, in this invention, a low molecular weight phenolic compound can be used, without heating, despite the limitation of glass transition temperature and melting | fusing point. Moreover, according to the photosensitive compound of this invention, the resist pattern which has a low LER can be formed.

Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings.

Detailed Description of Embodiments

The present invention provides a photosensitive compound for forming a resist pattern having a low LER even when used at a thin film thickness, a photosensitive composition containing the photosensitive compound, a method of forming a resist pattern, and a device manufacturing method.

In the present invention, LER is defined to be three times (3σ) the standard deviation of the line pattern width. For estimation of the LER, the line width is measured at 50 or more points sampled at equal intervals of 10 nm along the line length in a line pattern of length 0.5 to 2 μm, and the LER is calculated from this measured line width as a population. do. The width is measured by a scanning electron microscope, an atomic force microscope or the like.

The photosensitive compound which contains two or more structural units in the molecule represented by the said General formula (1) or (6) of this invention is nitrobenzyl alcohol derivative and phenolic hydride represented by following General formula (21) or (22) It can be synthesized by known condensation reaction of a compound containing two or more hydroxyl groups in a molecule (hereinafter referred to as "polyhydric phenol compound"):

In the formula, R ₁ to R ₆ are the same as defined above, and X is a hydroxyl group or a halogen atom.

In the formula, R ₁ to R ₆ are the same as defined above, and Y is a hydrogen atom or a halogen atom.

The polyhydric phenol compound used for the said condensation reaction is largely classified into a high molecular compound, the compound whose molecular weight is 2000 or less, and the low molecular compound which consists of 1 or more types of monomers. The polyhydric phenol compound has a low molecular weight compound, a weight average molecular weight (Mw) in the range of 1000 to 100000, preferably in the range of 3000 to 50000, molecular weight dispersion (Mw / Mn) of 1.0 to 3.0, preferably 1.0 to 1.5, more Preferably a high molecular compound of 1.0 to 1.2 is preferred. The smaller the molecular weight dispersion, the smaller the LER is imparted. In particular, a hydroxystyrene homopolymer having a weight average molecular weight of 3,000 to 50,000 and a molecular weight dispersion of 1.0 to 1.2 is preferable.

By the condensation reaction, phenol groups or groups are nitrobenzyl etherified or nitrobenzyl carbonated to give a unit structure represented by the general formula (1) or (6).

In the condensation reaction, not all phenol groups in the polyhydric phenol compound need to be nitrobenzyl etherified or nitrobenzyl carbonateized. It is preferable that at least two phenol groups in the molecule are nitrobenzyl etherified or nitrobenzyl carbonateized, and the nitrobenzyl etherification or nitrobenzyl carbonateization rate is preferably in the range of 10% to 90%, more preferably 10 Range from% to 50%. If the nitrobenzyl etherification rate or nitrobenzyl carbonation rate is higher than 90%, a large exposure dose is required for resist pattern formation, and since the polarity is low, the adhesion of the resist to the substrate to be processed is lowered. If the nitrobenzyl etherification rate is lower than 10%, the resistance of the resist pattern to the developer is low.

Condensation reactions are described, for example, in J. Org. Chem., 68, 9100 (2003) or J. Am. Chem. Known methods described in Soc., 110, 301 (1988) can be used.

Specific examples of the compound represented by the formula (21) include the following compounds:

2-nitrobenzyl alcohol, 2-nitrobenzyl chloride, 2-nitrobenzyl bromide,

2-methyl-2-nitrobenzyl alcohol, 2-methyl-2-nitrobenzyl chloride,

2-methyl-2-nitrobenzyl bromide, 3-methyl-2-nitrobenzyl alcohol,

3-methyl-2-nitrobenzyl chloride, 3-methyl-2-nitrobenzyl bromide,

5-methyl-2-nitrobenzyl alcohol, 5-methyl-2-nitrobenzyl chloride,

5-methyl-2-nitrobenzyl bromide, 3-chloro-2-nitrobenzyl alcohol,

3-chloro-2-nitrobenzyl chloride, 3-chloro-2-nitrobenzyl bromide,

4-chloro-2-nitrobenzyl alcohol, 4-chloro-2-nitrobenzyl chloride,

4-chloro-2-nitrobenzyl bromide, 5-chloro-2-nitrobenzyl alcohol,

5-chloro-2-nitrobenzyl chloride, 5-chloro-2-nitrobenzyl bromide,

4,5-dimethoxy-2-nitrobenzyl alcohol, 4,5-dimethoxy-2-nitrobenzyl chloride,

4,5-dimethoxy-2-nitrobenzyl bromide,

5- (3-iodopropoxy) -2-nitrobenzyl alcohol,

5- (3-iodopropoxy) -2-nitrobenzyl chloride,

5- (3-iodopropoxy) -2-nitrobenzyl bromide.

Specific examples of the compound represented by the formula (22) include the following compounds:

2-nitrobenzylformate, 2-nitrobenzylchloroformate, 2-nitrobenzylbromoformate,

2-methyl-2-nitrobenzylformate, 2-methyl-2-nitrobenzylchloroformate,

2-methyl-2-nitrobenzylbromoformate, 3-methyl-2-nitrobenzylformate,

3-methyl-2-nitrobenzylchloroformate, 3-methyl-2-nitrobenzylbromoformate,

5-methyl-2-nitrobenzylformate, 5-methyl-2-nitrobenzylchloroformate,

5-methyl-2-nitrobenzylbromoformate, 3-chloro-2-nitrobenzylformate,

3-chloro-2-nitrobenzylchloroformate, 3-chloro-2-nitrobenzylbromoformate,

4-chloro-2-nitrobenzylformate, 4-chloro-2-nitrobenzylchloroformate,

4-chloro-2-nitrobenzylbromoformate, 5-chloro-2-nitrobenzylformate,

5-chloro-2-nitrobenzylchloroformate, 5-chloro-2-nitrobenzylbromoformate,

4,5-dimethoxy-2-nitrobenzylformate, 4,5-dimethoxy-2-nitrobenzylchloroformate,

4,5-dimethoxy-2-nitrobenzylbromoformate,

5- (3-iodopropoxy) -2-nitrobenzylformate,

5- (3-iodopropoxy) -2-nitrobenzylchloroformate,

5- (3-iodopropoxy) -2-nitrobenzylbromoformate.

As a polyhydric phenol compound of a polymer, the vinylphenol type polymer or isopropenyl phenol type polymers, such as the condensation reaction product of a phenol and an aldehyde, the condensation reaction product of a phenol and a ketone, and poly (hydroxy styrene), can be illustrated.

Examples of ketones include acetone, methyl ethyl ketone, diethyl ketone or diphenyl ketone.

Examples of the phenol include monohydric phenols such as phenol, cresol, xylenol, ethyl phenol, propyl phenol, butyl phenol and phenyl phenol; And polyhydric phenols such as resorcinol, pyrocatechol, hydroquinone, bisphenol A, and pyrogallol.

Examples of aldehydes include formaldehyde, acetaldehyde, benzaldehyde or terephthalaldehyde.

Examples of ketones include acetone, methyl ethyl ketone, diethyl ketone or diphenyl ketone.

The condensation reaction of these phenols with aldehydes and the condensation reaction of phenols with ketones can be carried out by a conventional method. As a condensation reaction product of a phenol and an aldehyde, a phenol novolak resin, a cresol novolak resin, calix arene, etc. are mentioned. When condensation reaction is carried out using such a novolak resin or calix arene as the polyhydric phenol polymer compound, the hydrogen atoms of two or more phenolic hydroxyl groups are substituted with a substituent represented by the general formula (11) or (12), The novolak resin and the calixarene of the present invention are formed.

The vinyl phenolic polymer is selected from homopolymers of vinyl phenol (hydroxy styrene) and copolymers with components copolymerizable with vinyl phenol. Examples of the copolymerizable component include acrylic acid, methacrylic acid, styrene, maleic anhydride, maleimide, vinyl acetate, acrylonitrile, and derivatives thereof.

The isopropenyl phenolic polymer is selected from homopolymers of isopropenyl phenol and copolymers with components copolymerizable with isopropenyl phenol. Examples of the component that can be copolymerized include acrylic acid, methacrylic acid, styrene, maleic anhydride, maleimide, vinyl acetate, acrylonitrile and derivatives thereof.

Examples of low molecular weight polyhydric phenol compounds include compounds of carlix arene and compounds represented by the following formulas (31) to (36):

In the formula, R ₃₁ is an alkyl group having 1 to 4 carbon atoms, a phenyl group or a 1-naphthyl group; A plurality of R ₃₁ may be the same or different; p is an integer of 1 or more; q is an integer greater than or equal to 0 and p + q <= 6.

Wherein the symbol is the same as that of the formula (31); Z is a single bond, -S-, -O-, -CO-, -COO-, -SO-, -SO ₂ -or -C (R ₃₂ ) _2- (where R ₃₂ is a hydrogen atom, C1 to C) An alkyl group of 6, an acyl group of 2 to 11 carbon atoms, a phenyl group or a naphthyl group, and a plurality of R ₃₂ may be the same or different from each other) or a group represented by the following general formula (33).

In which R ₃₁ is the same as that of Formula (31); t is an integer of 0-4.

In which R ₃₁ is the same as that of Formula (31); R ₃₂ is the same as that of Formula (32); p, q, r, s, u and 각각 are each an integer of 0 or more; p + q≤5, r + s≤5, u + ｖ≤5 and p + r + u≥1.

In which R ₃₁ is the same as that of Formula (31); R ₃₂ and Z are the same as those of formula (32); A plurality of R ₃₁ are the same as or different from each other; A plurality of R ₃₂ are the same as or different from each other; p, q, r, s, u, ｖ, w and x are each an integer of 0 or more; p + q≤5, r + s≤5, u +, ≤5, w + x≤5, and p + r + u + w≥1.

In which R ₃₁ is the same as that of Formula (31); R ₃₂ is the same as that of Formula (32); A plurality of R ₃₁ are the same as or different from each other; A plurality of R ₃₂ are the same as or different from each other; p, q, r, s, u, ｖ, w and x are each an integer of 0 or more; p + q≤5, r + s≤5, u +, ≤5, w + x≤4 and p + r + u + w≥1.

The photosensitive compound of this invention produces | generates phenolic hydroxyl group which is an alkali-soluble group directly through photochemical reaction as shown to following Reaction formula (1) or (2). That is, the photosensitive compound functions as a positive resist in which the exposed portion is dissolved by the developer.

Scheme (1) shows the course of photochemical reaction of nitrobenzyl phenyl ether, and Scheme (2) shows the photochemical reaction of nitrobenzyl phenyl carbonate:

Scheme (1)

Scheme (2)

.

.

The photosensitive compound of the present invention can be dissolved in a solvent in the range of 2 to 50% by weight of solid content for use as a photosensitive composition. The photosensitive composition is preferably filtered with a filter having a pore diameter of about 0.1 to 0.2 mu m.

The solvent may dissolve the photosensitive compound of the present invention and may be freely selected without particular limitation as long as it does not cause a reaction with the photosensitive composition. The solvent may be a single solvent or a mixture of solvents. Examples of the solvent include ethers, esters, ether esters, ketones, ketone esters, amides, amide esters, lactams, lactones, and (halogenated) hydrocarbons. More specifically, as the solvent, ethylene glycol monoalkyl ethers, diethylene glycol dialkyl ethers, ethylene glycol monoalkyl ether acetates, propylene glycol monoalkyl ether acetates, propylene glycol monoalkyl ethers, propylene glycol di Alkyl ethers, acetate esters, hydroxy acetate esters, lactic acid esters, alkoxy acetate esters, cyclic or acyclic ketones, acetoacetic acid esters, pyruvic acid esters, propionic acid esters, N, N-dialkylformamides And N, N-dialkylacetamides, N-alkyl pyrrolidones, γ-lactones, (halogenated) aliphatic hydrocarbons, and (halogenated) aromatic hydrocarbons.

More specific examples of the solvent include ethylene glycol monomethyl ether,

Ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether,

Ethylene glycol mono-n-butyl ether, diethylene glycol dimethyl ether,

Diethylene glycol diethyl ether, diethylene glycol di-n-propyl ether,

Diethylene glycol di-n-butyl ether, ethylene glycol monomethyl ether acetate,

Ethylene glycol monoethyl ether acetate,

Ethylene glycol mono-n-propyl ether acetate,

Propylene glycol monomethyl ether acetate (PGMEA),

Propylene glycol monoethyl ether acetate,

Propylene glycol mono-n-propyl ether acetate, isopropenyl acetate,

Isopropenyl propionate, toluene, xylene, methyl ethyl ketone, cyclohexanone,

2-heptanone, 3-heptanone, 4-heptanone, ethyl 2-hydroxypropionate,

Ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxy acetate,

Ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutyrate,

3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate,

3-methyl-3-methoxybutyl propionate, 3-methyl-3-methoxybutyl butyrate,

Ethyl acetate, n-propyl acetate, n-butyl acetate, methyl acetoacetate,

Ethyl acetoacetic acid, methyl 3-methoxypropionate, ethyl 3-methoxypropionate,

Methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, N-methyl pyrrolidone,

N, N-dimethylformamide, N, N-dimethylacetamide, etc. are mentioned.

In view of safety, propylene glycol monomethyl ether acetate (PGMEA), 2-hydroxy ethyl propionate, cyclohexanone and the like are preferred.

The said solvent can contain 1 or more types of high boiling point solvents as needed. As the high boiling point solvent, benzyl ethyl ether, di-n-hexyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, acetonyl acetone, isophorone, caproic acid, caprylic acid, 1-octanol, 1- Nonanol, benzyl alcohol, benzyl acetate, ethyl benzoate, diethyl oxalate, diethyl maleate, γ-butyrolactone, ethylene carbonate, propylene carbonate, ethylene glycol monophenyl ether acetate.

The photosensitive composition of the present invention may contain a surfactant in the range of 0.2 parts by weight or less, preferably 0.001 to 0.05 parts by weight, more preferably 0.003 to 0.02 parts by weight based on the total amount (100 parts by weight) of the photosensitive compound. .

Examples of such surfactants include fluorine-based surfactants; Silicone surfactants; Polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether and polyoxyethylene oleyl ether; Polyoxyethylene aryl ethers such as polyoxyethylene octyl phenyl ether and polyoxyethylene nonyl phenyl ether; And polyoxyethylene dialkyl esters such as polyoxyethylene dilaurate and polyoxyethylene distearate.

Commercially available products of such surfactants include BM-1000 and BM-1100 (manufactured by BM Chemie); Megafack F142D, F144D, F171, F172, F173, F177, F178A, F178K, F179, F183, F184, F191 (manufactured by Nippon Ink Chemical Co., Ltd.), Florard FC-135, FC -170C, FC-171, FC-176, FC-430, FC-431; Megapak RS-1, RS-7, RS-9, RS-15, R-08 (manufactured by Sumitomo 3M), Surflon S-112, S-113, S-131, S-141 , S-145, S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (manufactured by Asahi Glass Co., Ltd.); F-Top EF301, EF303, EF352 (manufactured by Shin-Akita Kasei Co., Ltd.); SH-28PA, SH-190, SH-193, SZ-6032, SF-8428, DC-57, DC-190 (manufactured by Dow Corning Toray Silicone Co., Ltd.); Organosiloxane Polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), (meth) acrylic acid-based copolymer polyflow No. 57, No. 95 (manufactured by Kyoeisha Chemical Co., Ltd.), and phthalgent FT-250 , FT-251, FTX-218 (manufactured by Neos), and the like.

Moreover, the photosensitive composition of this invention can contain well-known additives, such as a coloring agent, an adhesion | attachment adjuvant, a storage stabilizer, and an antifoamer.

The photosensitive composition solution of the present invention may be coated with a known coating device such as a spin coater, dip coater, roller coater and the like. Coating film thickness is a range of 0.01-5 micrometers after prebaking normally depending on a use.

As a material of the board | substrate for photosensitive compositions, a metal, a semiconductor, glass, quartz, BN, an organic substance, etc. are mentioned. Such substrates may be coated with a film or films of resist, spin-on-glass material, organics, metals, oxides, nitrides and the like.

As a board | substrate apply | coated with the some kind of coating film, the board | substrate apply | coated by lamination | stacking of the resist layer which is sensitive to plasma etching, and the resist layer which is resistant to plasma etching is mentioned. Preferred examples are substrates formed in this order with a lower layer of resist sensitive to oxygen dry etching and a layer resistant to oxygen plasma etching.

Although a thermosetting phenol resin is mentioned as a lower resist layer, it is not limited to this.

The oxygen plasma resistant layer may be formed of, but is not limited to, SiO ₂ , TiO _2, or spin-on-glass material.

The lower resist layer is preferably formed in the range of 0.01 to 1 μm in thickness. The oxygen plasma etching resistant layer is preferably formed in the range of 0.001 to 1 ㎛ thickness.

The coating film of the photosensitive composition is suitably prefired at a temperature in the range of 50 ° C to 150 ° C, preferably 80 ° C to 110 ° C, depending on properties such as the boiling point of the solvent of the photosensitive composition. The prefiring can be performed by heating means such as a hot plate, hot air dryer.

The thus-coated photosensitive composition layer is selectively exposed to image radiation through a mask using a known exposure apparatus for pattern formation. Examples of the radiation for exposure include visible light, ultraviolet light, far ultraviolet rays, X-rays, electron beams, γ-rays, molecular rays, and ion beams. Also, mercury lamp beam (wavelength: 436 nm, 365 nm, 254 nm), KrF excimer laser beam (wavelength 248 nm), ArF excimer laser beam (wavelength 193 nm), F ₂ excimer laser beam (wavelength 157 nm), extreme ultraviolet light Ultraviolet rays such as (EUV, wavelength: 13 nm), or electron beams are preferable. One or more radiations may be used.

The exposure may also be performed by near-field light generated by a photomask having a light absorber having an aperture width narrower than the wavelength of the exposure light source. For exposure of near field light, the radiations can be used. The radiation may be performed with a single beam or two or more beams. The near field exposure is performed by bringing the light absorber into proximity to the exposed object (e.g., in contact with the exposed object) so that the near field light can reach the exposed object.

For finer resist patterns, shorter wavelengths of light, such as ArF excimer laser beams, F ₂ excimer laser beams, EUV beams, electron beams or near field light unaffected by diffraction limits, are particularly preferred for exposure.

The photochemical reaction of the photosensitive composition of this invention differs from the photochemical reaction of the conventional chemically amplified resist as mentioned later. 1 and 2B, the range in which one photon can cause a deprotection reaction is defined as the photoreaction point 103. In the conventional method, one photon (hν) incident on the resist layer 204 generates one acid, diffuses by promotion by heat applied before development, using the acid as a catalyst, and protects with an acid-decomposable protecting group. The deprotection reaction of the plurality of alkali soluble groups 201 is caused, thereby providing the plurality of alkali soluble groups 102. Therefore, the size of the photoreaction point of the chemically amplified resist is about 10 nm. On the other hand, in the present invention, heat treatment before development is unnecessary, so that one photon induces deprotection of one group in one molecule of the photosensitive compound of the present invention. That is, one photon hν introduced into the resist layer generates one free alkali soluble group 102 from one alkali soluble group 101 protected by a photodegradable protecting group. Therefore, the photoreaction point in this invention has a molecular scale (range of 0.1-1 nm). By this, the LER of the resist pattern can be reduced.

After exposure, the exposed portion (irradiation portion) of the photosensitive resist layer is developed and removed, the resist is washed and dried to obtain an intended resist pattern.

For development, an alkaline aqueous solution containing the compound exemplified below is used as the developer: sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, diethylamine, di -n-propylamine, triethylamine, methyldiethylamine, dimethylethanolamine, triethanol amine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo [5.4. 0] -7-undecene and 1,5-diazabicyclo [4.3.0] -5-nonene. The developer can contain a water-soluble organic solvent, for example, alcohols such as methanol and ethanol, and an appropriate amount of a surfactant. Particular preference is given to an aqueous 2.38% by weight tetramethylammonium hydroxide solution.

The development is carried out by, for example, immersion, spraying, brushing, slapping or the like.

When the resist pattern film is formed on a substrate on which a lower resist layer and an oxygen plasma resistant layer are formed in this order, the oxygen plasma resistant layer is first etched using the resist pattern as a mask. Etching may be performed by wet etching or dry etching. Dry etching is more preferable as it is suitable for fine pattern formation. Etching agents for wet etching are selected according to the etching target, and examples thereof include aqueous hydrofluoric acid, aqueous ammonium fluoride, aqueous phosphoric acid, aqueous acetic acid, aqueous nitric acid and aqueous cerium ammonium nitrate. Examples of the dry etching gas include CHF ₃ , CF ₄ , C ₂ F ₆ , SF ₆ , CCl ₄ , BCl ₃ , Cl ₂ , HCl, H ₂ , Ar, and mixtures thereof.

Next, oxygen plasma etching is performed using the oxygen plasma resistant layer on which the pattern is formed as a mask. Examples of the oxygen-containing gas for oxygen plasma etching include oxygen alone, a mixed gas of oxygen and an inert gas such as argon, or a mixed gas of oxygen and carbon monoxide, carbon dioxide, ammonia, dinitrogen monoxide, sulfur dioxide, and the like.

By the above two-step etching, a resist pattern having a higher aspect ratio than the resist pattern formed by exposure and development can be formed.

Dry etching or wet etching is performed to substrates, such as semiconductor substrates, such as a silicon and germanium, using the resist pattern formed in this way as a mask. Metal deposition, lift-off, plating and the like are further performed on the substrate to produce the desired device on the substrate. For example, a semiconductor device can be created as follows.

First, a device circuit of a semiconductor is designed. Next, a mask having a circuit pattern corresponding to the intended circuit is produced. Separately, the board | substrate for devices, such as a silicon wafer, is prepared, and the photosensitive composition of this invention is laminated | stacked on it.

Next, a circuit is formed on the substrate by lithography by the mask and the conventional exposure apparatus. The circuit forming step includes forming an oxide film, etching, forming an insulating film, forming a wiring conductive film, patterning, and the like. Then, the substrate having the circuit is chipped through an assembly process (dicing, bonding), packaging, or the like.

[ Example ]

Next, the present invention will be described in detail with reference to Examples.

Example  One

Synthesis of Photosensitive Compound

40 ml of N, N-dimethylformamide in a 100 ml reactor, 4.0 g of poly (hydroxystyrene) (PHS) (33.3 mmol in terms of hydroxystyrene monomer, defined as 1.0 molar equivalent) under a nitrogen atmosphere. Dissolved in. The said poly (hydroxy styrene) (PHS) is a weight average molecular weight (Mw) 4,100, and molecular weight dispersion (Mw / Mn) 1.1.

 To this solution, 0.21 g (8.75 mmol, 0.265 molar equivalents) of sodium hydride was added at room temperature (23 ° C), and the obtained mixture was stirred for 30 minutes, and further stirred at 50 ° C for 2 hours.

To this suspension was added 2.15 g (7.8 mmol, 0.235 molar equivalents) of 4,5-dimethoxy-2-nitrobenzylbromide at once, and the mixture was stirred at 50 ° C for 1 hour.

0.21 g (8.75 mmol, 0.265 molar equivalent) of sodium hydride was added to this solution again, and the mixture was stirred for 1 hour.

Thereafter, 2.15 g (7.8 mmol, 0.235 molar equivalents) of 4,5-dimethoxy-2-nitrobenzylbromide was added to this suspension at once, and the mixture was stirred at 50 ° C for 2 hours.

The resulting solution was stirred at room temperature without heating for 18 hours.

To this solution was added 100 ml of a 10% aqueous ammonium chloride solution. The aqueous phase was extracted three times with 100 ml of ethyl acetate. The organic phase portions were combined, and the combined organic phases were washed eight times with 100 ml and once with 100 ml of saturated aqueous sodium chloride solution. The washed organic phase was dried over anhydrous magnesium sulfate and concentrated.

Toluene was added to this solution to precipitate the target polymer. The supernatant was removed, toluene was added thereto again, and the polymer was suspended. The supernatant was left to stand and then removed.

This viscous polymer was dissolved in 80 ml of ethyl acetate and slowly added dropwise to 1.2 l of hexane. The reprecipitated crystals were filtered off, washed with hexane and dried under high vacuum to give a pale yellow solid photosensitive compound A (nitrobenzyl ether group introduction ratio: 38%).

The synthetic route of the photosensitive compound A is shown in the following scheme (3):

Scheme (3)

In formula, m and n are all integers 0 or more.

Through the same synthetic route as the above-mentioned photosensitive compound A, the addition amount of sodium hydride and 4,5-dimethoxy 2-nitrobenzyl bromide was changed to carry out the synthesis, to obtain a photosensitive compound. As a result, photosensitive compound B (nitrobenzyl ether group introduction rate: 26%), photosensitive compound C (nitrobenzyl ether group introduction rate: 20%), and photosensitive compound D (nitrobenzyl ether group introduction rate: 16%) were obtained. .

Example  2

Adjustment of the photosensitive composition

The photosensitive compounds A to D were dissolved in propylene glycol monomethyl ether acetate (PGMEA) at a concentration of 10% by weight, respectively, to obtain photosensitive compositions A 'to D'.

Further, the photosensitive compounds A to D were dissolved in PGMEA so as to have a concentration of 1.25% by weight, respectively, to obtain photosensitive compositions A ″ to D ″.

Example  3

Of photosensitive compound Developing resistance  evaluation

The 10 wt% PHS solution (PHS has a weight average molecular weight (Mw) 4,100, molecular weight dispersion (Mw / Mn) 1.1) in the photosensitive compositions A 'to D' and PGMEA was treated with hexamethyldisilazane (HMDS). Each was applied by spin coating on a Si substrate.

Subsequently, the substrate to which the composition was applied was heated at 90 ° C. for 90 seconds on a hot plate to obtain five coating films of photosensitive compounds A to D and polyhydroxystyrene (PHS) formed on the substrate.

The five substrates were immersed in a 2.38 wt% tetramethylammonium hydroxide aqueous solution. The film thickness before and after dipping was measured using the spectroscopic ellipsometer, and the dissolution rate (nm / s) in a developing solution was computed.

3 shows the dependence of the dissolution rate on the developing solution on the nitrobenzyl ether group introduction ratio of the photosensitive compound. The photosensitive compound A (nitrobenzyl ether group introduction ratio: 38%) has a dissolution rate of less than 0.001 nm / s, and the rate is beyond the range of FIG. 3.

In general, the developing speed of the unexposed portion of the positive resist is preferably 0.1 nm / s or less. Accordingly, it was found that the photosensitive compounds A and B (nitrobenzyl ether group introduction ratios: 38% and 26%, respectively) were suitable as positive resists.

Since the film thickness change in the developer immersion test of the photosensitive compound A was less than the measurement limit of the spectroscopic ellipsometer, the development speed could not be measured.

Example  4

Of photosensitive compound Extinction coefficient  Measure

The extinction coefficient of the coating film of the photosensitive compounds A-D formed in Example 3 was measured using the spectroscopic ellipsometer. 4 shows the extinction coefficients of the coating films of the photosensitive compounds A to D and PHS in the wavelength range of 200 nm to 500 nm. It has been found that the photosensitive compounds A to D have light absorption in the range of 420 nm or less in wavelength.

Example  5

Near field  By exposure Resist  Formation of patterns (1)

On Si substrates, a thermosetting phenol resin 100 nm thick (Rohm & Haas Co., AR2455) and a spin-on-glass material 20 nm thick (Honeywell, T-03AS) Were laminated by spin coating in this order.

The surface of the spin-on-glass material layer was treated with hexamethyldisilazane (HMDS).

Comparative photosensitive composition M was prepared as follows. That is, with respect to 100 parts by weight of a chemically amplified positive resist (TDUR-P308EM, manufactured by Tokyo Okaka Co., Ltd.) for KrF excimer laser exposure made of poly (hydroxystyrene), a photo acid generator (PAG) (Chiba Specialty) 5 parts by weight of Chemicals, CGI1397) was added. This mixture was diluted with propylene glycol monomethyl ether acetate (PGMEA) to make photosensitive composition M.

The photosensitive composition A "or the photosensitive composition M was apply | coated by spin coating so that the thickness after heating might be set to 20 nm, respectively, on the board | substrate produced above, and it heated on 90 degreeC on 90 degreeC, and produced the resist-coated board | substrate.

The photomask for near-field exposure includes a 50 nm thick amorphous Si film having a line-and-space pattern of 90 nm pitch and a space width of about 30 nm, and a 400 nm thick support silicon nitride film (transparent substrate). Prepared was composed of. The photomask has a membrane structure so that the light absorbing layer and the silicon nitride film can be elastically deformed so as to be in proximity to (eg contact with) the resist-coated substrate.

The photomask is provided with a gap of 50 mu m in parallel with the resist-coated substrate. The photomask was contacted with the resist-coated substrate by deforming the membrane by applying pressure from the transparent substrate side.

In this state, i-ray light (wavelength: 365 nm, illuminance: 250 mW / cm 2) of an ultra-high pressure mercury lamp was irradiated from the transparent substrate side through an i-line bandpass filter. Since the opening space width of the light absorbing layer was about 30 nm and narrower than the wavelength of the projection light, radio wave light was shielded and only near-field light (wavelength 365 nm) was introduced into the resist film in close contact with the light absorbing layer.

Immediately after near field exposure, the resist coated substrate coated with the photosensitive composition A ″ was immersed in a 2.38 wt% tetramethylammonium hydroxide aqueous solution for 10 seconds, rinsed with distilled water for 20 seconds to form a resist pattern having a pitch of 90 nm.

On the other hand, the resist-coated substrate coated with the photosensitive composition M was heated for 90 seconds at 110 ° C on a hot plate after near-field exposure, and immersion and rinsing were performed in the same manner as described above.

The exposure amount was changed to form several resist patterns. 5A and 5B are atomic force microscope (AFM) images of the highest resolution resist pattern on each substrate. 5A is an atomic force micrograph of a resist pattern with a pitch of 90 nm of the photosensitive composition M, and FIG. 5B is an atomic force micrograph of a resist pattern with a pitch of 90 nm of the photosensitive composition A ″.

As indicated above, the photosensitive composition A ″ of the present invention made it possible to form a resist pattern having a sufficiently small LER compared to the photosensitive composition M. FIG.

Example  6

Near field  By exposure Resist  Formation of patterns (2)

In the same manner as in Example 5, two kinds of resist-coated substrates coated with the photosensitive composition A ″ having a film thickness of 20 nm or 10 nm and three kinds coated with the photosensitive composition M having a thickness of 30 nm, 20 nm or 10 nm The resist-coated substrate of was prepared.

A photomask similar to that of Example 5 was used except that the pattern on the amorphous light absorbing layer had a pitch of 160 nm and a space width of about 60 nm. The near-field exposure was performed to the resist-coated board | substrate with which the photomask was stuck.

After exposure, the resist-coated substrate was heated and developed to form a resist pattern having a pitch of 160 nm.

On each resist-coated substrate, the exposure amount was changed to form a resist pattern. 6-10 are atomic force micrographs of resist patterns with the highest resolution of each pattern.

As shown in the atomic force micrograph, the photosensitive composition M tended to be given a larger LER at a small film thickness of 30 nm to 10 nm. On the other hand, the photosensitive composition A "of this invention gave the resist pattern of small LER also with respect to the film thickness of 10 nm.

The photosensitive composition M gave a large LER at a film thickness of 10 nm, which is presumably due to the fact that the composition ratio of the composition on the substrate was deviated by diluting the multi-component photosensitive composition M with PGMEA for the purpose of thinning. It became.

In addition, it is generally known that chemically amplified resists cause an acid generated in an exposed portion to be neutralized on the surface by a basic component present in an environmental atmosphere, resulting in pattern abnormality. This influence could be remarkable in the film thickness of 10 nm or less.

As mentioned above, according to this invention, the formation method of the resist pattern using the photosensitive composition which can form the resist pattern which has a small LER, and the manufacturing method of the device using the said resist pattern can be provided.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the present invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent constructions and functions.

Claims (19)

Photosensitive compound characterized by including two or more structural units represented by the following general formula (1) in a molecule | numerator:

(Wherein R ₁ is a hydrogen atom or an alkyl group; at least one of R ₂ , R ₃ , R ₄ , R ₅ and R ₆ is a nitro group, and others are hydrogen atoms, halogen atoms, alkyl groups, alkoxy groups, phenyl groups) , A naphthyl group, and a group selected from the group consisting of alkyl groups in which some or all of the hydrogen atoms are substituted with fluorine atoms, R ₇ is a substituted or unsubstituted phenylene group or a naphthylene group. The photosensitive compound according to claim 1, comprising two or more structural units represented by the following general formula (2) in a molecule:

Wherein R ₇ is as defined in claim 1. The photosensitive compound according to claim 1, wherein two or more structural units represented by the following general formula (3) are included in the molecule:

Wherein R ₇ is as defined in claim 1. The photosensitive compound according to claim 1, wherein two or more structural units represented by the following general formula (4) are included in the molecule:

Wherein R ₇ is as defined in claim 1. The photosensitive compound according to claim 1, wherein two or more structural units represented by the following general formula (5) are included in the molecule:

Wherein R ₇ is as defined in claim 1. A photosensitive compound comprising two or more structural units represented by the following general formula (6) in a molecule:

(Wherein R ₁ is a hydrogen atom or an alkyl group; at least one of R ₂ , R ₃ , R ₄ , R ₅ and R ₆ is a nitro group, and others are hydrogen atoms, halogen atoms, alkyl groups, alkoxy groups, phenyl groups) , A naphthyl group, and a group selected from the group consisting of alkyl groups in which some or all of the hydrogen atoms are substituted with fluorine atoms, R ₇ is a substituted or unsubstituted phenylene group or a naphthylene group. The photosensitive compound according to claim 6, wherein the photosensitive compound comprises two or more structural units represented by the following general formula (7):

Wherein R ₇ is as defined in claim 6. The photosensitive compound according to claim 6, wherein two or more structural units represented by the following general formula (8) are included in the molecule:

Wherein R ₇ is as defined in claim 6. The photosensitive compound according to claim 6, wherein two or more structural units represented by the following general formula (9) are included in the molecule:

Wherein R ₇ is as defined in claim 6. The photosensitive compound according to claim 6, wherein the photosensitive compound comprises two or more structural units represented by the following general formula (10):

Wherein R ₇ is as defined in claim 6. The hydrogen atom of two or more phenolic hydroxyl groups is substituted by the substituent represented by the following general formula (11) or (12), The poly (hydroxy styrene) characterized by the following:

(Wherein R ₁ is a hydrogen atom or an alkyl group; at least one of R ₂ , R ₃ , R ₄ , R ₅ and R ₆ is a nitro group, and others are a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, Phenyl group, naphthyl group, and alkyl group in which some or all of the hydrogen atoms are substituted with fluorine atoms. Wherein the hydrogen atom of two or more phenolic hydroxyl groups is substituted with a substituent represented by the following general formula (11) or (12):

(Wherein R ₁ is a hydrogen atom or an alkyl group; at least one of R ₂ , R ₃ , R ₄ , R ₅ and R ₆ is a nitro group, and others are hydrogen atoms, halogen atoms, alkyl groups, alkoxy groups, phenyl groups) , A naphthyl group, and an alkyl group in which some or all of the hydrogen atoms are substituted with fluorine atoms. The novolak resin characterized by the hydrogen atom of two or more phenolic hydroxyl groups substituted by the substituent represented by the following general formula (11) or (12):

(Wherein R ₁ is a hydrogen atom or an alkyl group; at least one of R ₂ , R ₃ , R ₄ , R ₅ and R ₆ is a nitro group, and others are hydrogen atoms, halogen atoms, alkyl groups, alkoxy groups, phenyl groups) , A naphthyl group, and an alkyl group in which some or all of the hydrogen atoms are substituted with fluorine atoms. A photosensitive composition comprising dissolving at least one kind of the compound according to any one of claims 1 to 13 in an organic solvent. Providing a photosensitive resist layer according to claim 14 on a substrate to form a photosensitive resist layer; Selectively irradiating the resist layer with radiation; And And forming a pattern of the resist layer by developing the radiation irradiator. The photosensitive resist layer according to claim 15, wherein the resist layer removable by plasma etching and another resist layer resistant to plasma etching are laminated on the substrate, and then the photosensitive resist layer is formed on the layer resistant to plasma etching. A method of forming a resist pattern, characterized by the above-mentioned. The method of forming a resist pattern according to claim 15, wherein said photosensitive resist layer is formed with a layer thickness of 20 nm or less. The method of claim 15, wherein the irradiation of the radiation is performed by near-field light. A device is formed on a substrate by using the method of forming a resist pattern according to claim 15.

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